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The greatest part of the sulphur unites itself with the metal form ing a sulphuret, azote, or rather carburetted azotic gas, is given off, a portion of the carbon remains long behind, and by the increase of heat and the free admission of air it glows like a pyrophorus, a little before the temperature rises to redness. After this pyrophoric appearance, but not before, sulphate of's copper may be washed out of copper anthrazothionhydrate, / 4. The metallic sulphuret which remains behind after the hydrate has been exposed to a red heat without the access of air, contain's the metal in the metallic state. Nitric acid dissolves it when assisted by heat with the evolution of abundance of nitrous gas, and leaves the sulphur behind. 5. The copper anthrazothionhydrate is not sensibly attacked by concentrated muriatic acid even at a boiling temperature, provided care be taken not to allow any oxidizing substance to come in contact with it; but if a little of any such substance, for example, of chlorate of potash, be added, the copper is oxidized, and the anthrazothion decomposed. If this muriatic solution be evaporated to dryness, and the dry mass mixed with potash ley, a strong smell of ammonia becomes perceptible. Now if the metal in this compound were in the state of an oxide, concentrated muriatic acid would surely be capable of separating the acid from the oxide, as it does from all the alkaline anthrazothionates, and even with much greater facility ; but this, however, is not the case. The muriatic acid is never able to dissolve the metal till an oxidizing body comes into play and gives out its oxygen to the metal.s. 6. During the combination of anthrazothionic acid with easily 1 reducible metals, the former must undoubtedly reduce the latter, because three of its elements, namely, hydrogen, sulphur, caran bon, are capable of reducing not only these, but many others to 's that state, and the fourth element, azote, is at least neutral, if it does not rather promote disoxidation. Ought not then the hydrogen, the most disoixdizing of all the elements, be capable of si reducing these oxides to the metallic state, since the water ) thereby produced may combine with the metallic anthrazothion (or anthraxothionide, if that name be preferred) and forma hydrate? 7. To show in the last place that the opinion which I. entertain respecting these compounds is at least not more hypow.. thetical than Porrett's, I may observe that hitherto nobody has been capable of deciding certainly about the way in which the. elements are united in a compound. Nobody can, for example, in this case show that the hydrogen of the acid does not unite with the oxygen of the oxide (which from the preceding obser-: vations is highly probable); but that the former remains in the acid, and the latter in the oxide, after these two have united together and constituted a new body. In this point of view quantities than anthrazothion; because some of the cyanogen compounds are prea pared on a large scale, and may be had in quantities, while no anthrazothion compounds are to be met with in apothecaries' shops.

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both opinions appear equally valid ; while the former, from the reason stated, and from the properties of the metallic anthrazola thionhydrates, seems to me much more likely to be the true one.,i..)

Sect. 12. Properties of some metallic Anthrazothionhydrates, -Q. That of silver is white, curdy, and very voluminous ; it has some resemblance to muriate of silver, and becomes black by exposure to the atmosphere, at least if it has been treated with ammonia and well washed, but it does not become so black as muriate of silver, from which it is very easily distinguished, asi" 11 it is not soluble in ammonia. In this respect it resembles iodide. of silver, with which, however, it cannot be compared in its other properties. Liquid chlorine forms with it muriate of silver, sulphur is precipitated, ammonia formed, and carbonic acid gas evolved. Chlorine produces the same effect upon all the other metallic anthrazothionhydrates.

b. The anthrazothionhydrate of gold is capable of assuming different colours, according to the way that it is prepared. When treated with muriatic acid and water, it becomes gradually of a dark purple colour. When the dark precipitate is put into a concentrated solution of anthrazothionate of potash, it assumes a light flesh colour, doubtless because it enters into . combination with a little of the anthrazothionate of potash. Should not the analogy of the formation of white prussiate of iron be attended to here? When the flesh coloured substance is.i. put into muriatic acid, it becomes dark purple. Potash deprives : it of a part of its anthrazothion, and gives it a yellow colour. The precipitate when first formed, and even after being dried, is very voluminous. The anthrazothionide of gold is soluble in liquid anthrazothionate of potash, and the solution has a dark red colour. I added an excess of anthrazothionate of potash to a neutral solution of gold in muriatic acid, and then filtered the liquid - it passed through the filter dark red. Some drops of ammonia threw down a black powder from this liquid, and the dark red colour disappeared.

c. The anthrazothionhydrate of mercury is white and bulky, and is formed by double decomposition only when the metal is in solution in an acid in the state of protoxide. The solution of corrosive sublimate is not precipitated by anthrazothionate of potash; but if a piece of tin be put into the mixture, the anthrazothionhydrate of mercury is precipitated mixed with metallic mercury. It would seem that when the metal of an anthrazo. thionhydrate contains: more oxygen than the hydrogen of the acid is capable of taking up, and when in this state it is in solution in an acid, it is capable of forming with anthrazothionie acid by means of double decomposition a soluble anthrazothionate, but not an anthraxothionhydrate.

d. The anthrazothionhydrate of platinum is yellowish, bulky, and easily soluble both in acids and in liquid muriates. From

these last solutions, alcohol throws down the hydrate in yellowish white flocks.*

The alkalies and the non-oxidizing acids, when no oxygen can interfere, appear incapable of producing any effect upon the metallic anthrazothionhydrates.

Sect. 13. Anthrazothionate of Iron.--This compound when seen by transmitted light appears blood-red; by reflected light it appears quite black, though now and then it shows a dark green metallic lustre on the surface. It deliquesces in the air, and cannot be obtained in the state of crystals. Acids deprive it of its iron oxide, and alkalies of its acid. In both cases the peculiar colour which distinguishes it disappears. It is exceedingly soluble in absolute alcohol, which enables us to obtain it in a state of great purity; it has a disagreeable, styptic, metallic taste. This property which anthrazothionic acid has of striking a strong red colour with oxide of iron renders the anthrazothionate of potash a very useful reagent for detecting the presence of that metal. It is incomparably a more delicate test than prussiate of potash, though not quite so delicate as the infusion of nut-galls. When an alkaline carbonate is present in a mineral water together with carbonate of iron, as is the case in Gelenauer water, in that case neither anthrazothionate of potash nor prussiate of potash is capable of detecting the presence of the iron ; we must, therefore, in the first place, neutralize the carbonate by means of a stronger acid; then the liquid will strike a red colour with anthrazothionate of potash. The red colour of anthrazothionate of iron, when applied to organized bodies, as skins, paper, linen, wool, silk, is very fugitive, because the acid gradually makes its escape. Perhaps it might be fixed by means of a mordant.

Sect. 14. Constituents of Anthrazothionhydrate of Copper. This compound is formed when anthrazothionate of potash is mixed with a solution of copper and a disoxidizing body, as, for example, sulphate of iron is added to the mixture. From the origin of this white, bulky precipitate, described by Porrett, it seems to follow that the hydrogen in the acid is not sufficient to convert the whole oxygen of the oxide into water. Hence the reason why the assistance of a disoxidizing substance is necessary for the formation of the hydrate. Porrett considers this compound as an anthrazothionate of copper, and states its constituents at 36.855 acid and 63•145 oxide of copper. But it contains a notable quantity of water, though Porrett affirms the contrary, even when it has been long dried in as high a temperature as it can be exposed to without altering its white colour (which would indicate a decomposition); for when it is heated

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* The properties of the anthrazothionhydrate of copper have been already described by Porrett.

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in a glass tube, large drops of water are deposited in the cool part of the tube. We must, therefore, consider it as a hydrate; and the proportions of the constituents as given by Porrett require to be altered.

Three grains of the hydrate being exposed to heat till they became dark coloured gave out gr. of water. Hence it follows that of the weight of this hydrate is water.

It is obvious likewise that the metal must exist in the hydrate in the metallic state, since the hydrogen of the acid reduces the oxide, a fact which can be evidently observed even during the formation of this hydrate; for when the alcoholic solution of anthrazothionate of potash is mixed with liquid acetate of copper, we can perceive at the instant of the mixture a brown copper colour upon the surface of the liquid, which disappears after the hydrate is completely formed. In this case either the alcohol or the acetic acid must act the part of a disoxidizing body. The necessity of the presence of this intermediate substance shows that the hydrate can be formed only by means of the sum of the affinities of the oxygen for the hydrogen, and of the anthrazothion for the metal.

Sect. 15.-As we can employ as disoxygenizing substances bodies which possess that property in a far smaller degree than is necessary to change the peroxide of copper into protoxide, it follows as a consequence that these disoxygenizing substances actually separate from the oxide much less oxygen than would be requisite in order to convert it into protoxide. The remaining part of the task is performed by the hydrogen of the anthrazothionic acid. We will assume, therefore, that the disoxygenizing medium deprives the oxide of įth of its oxygen, while the remaining ths unite themselves to the hydrogen of the acid at the same instant that the metal combines with the anthrazothion, and with the water produced forming an anthrazothionhydrate of copper. The accuracy of this assumption will still further appear from this, that we shall find in quite another way exactly as much hydrogen in the acid of the hydrate as is sufficient for saturating ths of the oxygen, which the oxide contains. I may mention as a second corroboration of the truth of this assumption, that the hydrate contains exactly as much water as is capable of being formed by the union of ths of the oxygen of the oxide with the hydrogen of the acid; namely, th of the weight of the whole compound as was shown in the last paragraph,

Sect. 16.-Porrett found that 4:58 gr. of anthrazothionhydrate of copper contain 2.56 gr. of metal, which require 0:64 gr. oxygen to be converted into oxide. According to our view of the subject, įth of this oxygen = 0.128 gr. unites with the disoxygenizing medium. There remain, therefore, ths of 0:64 = 0·512 gr. of the oxygen, which unite with the hydrogen of the anthrazothionic acid to form water. When, therefore, 2.56 Vol. XIII, No.

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3.07 =

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gr. metal + 0:512 gr. oxygen = 3.07 gr. is subtracted from the sum total of hydrate, we obtain the quantity of acid; but 4:58

1:51, which must be the amount of the acid. These 1:51

gr. of acid must contain 0.067 hydrogen, because this is the quantity requisite to convert 0:512 gr. of oxygen into 0-578 gr. of water. Hence it follows that 4:580 gr. of anthrazothionhydrate of copper contain 2.56 gr. of copper, 1.510 gr. of anthrazothionic acid, and 0.512 gr. of oxygen, or according to the accurate way of viewing this compound, that not the acid but the anthrazothion is united with the metal and with the water, the constituents are, Copper.

2-560 Anthrazothion.... 1.442 (= 1.510 acid

1.442 (= 1.510 acid - 0.067 hydrogen) Water

0:578 = 0.511 oxygen + 0.067 hydrogen) 4.580

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A Method of separating Iron from Manganese.

By Theodor von Grotthuss.* DISSOLVE the metal, or the oxide, in muriatic acid ; and as it is necessary to convert the iron into a peroxide, pour a few drops of nitric acid into the solution, and evaporate it till it becomes doughy and merely moist. Pour over it, when in this state, a solution of anthrazothioniate of potash in alcohol, and mix the whole well together. The liquid becomes immediately of a blood red colour, because anthrazothionate of iron is formed which dissolves in the alcohol. The anthrazothionate of manganese falls down in the state of a white powder, because it is not soluble in absolute alcohol. Add a portion of alcohol, filter the liquid, and wash the white insoluble anthrazothionate of manganese repeatedly with small portions of alcohol. It will be manifest that the manganese is quite freed from all admixture of iron when the alcohol comes off from it quite colourless. The oxide of iron may be precipitated from the red liquid by means of potash ley,

* Translated from Schweigger's Journal, xx. 272.

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